[1] The former Portland Railroad Company Substation is located in southwestern Scarborough (the area known as Dunstan Corner), on the north side of US 1, at the back of a parking lot separating the Scarborough Fire Station and Alger Hall, the local Masonic lodge.

Original pedestrian entrances (some now closed off) were located on the southwest and northeast sides of the front block, and also in the larger rear section.

The interior of the building has no original equipment related to its use as an electrical power substation, and now houses exhibits of the Scarborough Historical Society.

[2] The building was erected in 1911 as a power substation for the Saco Division of the Portland Railroad Company, a trolley operator in southern Maine.

It is the best preserved building from the state's period when it had an extensive light rail network, most of the others having been either demolished or substantially altered for other purposes.